My theory - M’benga’s daughter had a degenerative disease and her pattern was stable enough to put into the buffer.

But Batel’s problem is she has loads of living Gorn inside her, and so has Gorn DNA in very close proximity to her own. At one point they even say they’re co-dependent on each other. They probably didn’t want to end up with a “The Fly”/Tuvix situation.

I’m sure it wouldn’t work for <insert technobabble reason here>, but this is the unfortunate consequence of treating it so casually in season one…